Carburetor



W. H. WEBER Nov. 17, 1936.

CARBURETOR Filed June 12, 1935 6 Shets-Sheet 2 n2 em QM 21 E ma PM? E? Q29: m m W 2 a l 6% m2 um m: 6 m a my Q. .2 s a 3. m 0& 3; 22 m m mm. m2 0 Q 2 0 W Q v I m l- N O .m m. 7 ms N. w 2. E m 5 T g INVENTOR M/KM M ATTORNEY Nov 17, 1936.

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W. H. WEBER CARBURETOR Filed June 12, 1935 6 Sheets-Sheet 3 INVENTOR W KM ATTORNEY Nov. 17 1936. w. H. WEBER 2,061,494

CARBURETOR Filed June 12, 1935 6 Sheets-Sheet 4 FIG. 9 INVENTOR Pie 8 BWKM :0 ATTORNEY Nov. 17, 1936. w. H. WEBER a CARBURETOR Filed June 12, 1955 6 Sheets-Sheet 5 Wm. I

' 0 ATTORNEY Nov. 17, 1936. w. H. WEBER 2 L CARBURETOR Filed June 12, 1935 6 Sheets-Sheet 6 FIG. l6

'- INVENTOR W N. Wm

%, ATTORNEY reamed Nov. W, 1936 iLJNl'lED sTATEs PATENT OFFICE 2,061,494 GARBURETOR Walter ii. Weber, Detroit, Mich., assignor to Detroit Lubricator Company, Detroit, Mich, a corporation of Michigan Application June 12,1935, Serial No. 26,290

43 Claims. (oi. 261-46) My invention relates to new and usefulim out the range of engine operation, supplyingthereto a properly proportioned explosive mixture of air and fuel.

Another object is to provide means to control the quantity of fuel supplied soas to maintain the proper air-fuel ratio throughout engine operation.

Another object is to provide means to augment the supply of fuel for engine'acceleration.

Another object is to provide a carburetor which is particularly adapted to draw or lift fuel to its constant level reservoir from a lower level supply tank while maintaining a highly m 'eflicient carburetion of fueland adequate supply thereof to the engine. I

Another object is to provide novel means for regulating the ratio of fuel to air.supplied by the carburetor.

The invention consists in the improved construction and combination of parts, to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawings, to be taken as a partof this specification, I have fully and clearly illustrated several carburetors embodying my invention, in which drawings- Figure 1 is a top plan view of a carburetor embodying my invention;

Fig. 2 is a view thereofin side elevation;

Fig.3 is a view in side or end elevation, looking from left to right facing Fig. 1; I

Fig; 4 is a view in vertical central section on the line i i of Fig. 1, taken in the direction of the arrows;

Fig. 5 is a view in side or end elevation with certain parts broken away to show internal structure and looking from right to left facing Fi 1;

ig. 6 is a detail view in vertical section on the line 5-6 of Fig. 1;

Fig. '7 is a detail view in vertical section on the line i"i of Fig. 1;

Fig. 8 is a detail view in vertical section on the line 8-8 of Fig. 9;

Fig. 9 is a view in horizontal section on the line 9-4! of Fig. 2;

Fig. 10 is a diagrammatic view showing the t relation of the ports and passages and the mechanical structure ofthe carburetor shown in Figs. 1 to 9 inclusive;

Fig. 11 is a top plan'view with certain parts broken away to show the internal structure of anothencarburetor embodying my invention;

Fig. 12 is an end or side view in elevation with certain parts broken away and partly in section,

looking from left to right facing Fig. 11;

. Fig. 13 is a view in side elevation, looking from left to right facing Fig. 12;

10 Fig. 14 IS a view in vertical central section on the line M-M of Fig. 11;

Fig. 15 is a detail view. in vertical section on the line l5-l5 of Fig. 11;

Fig. 16 is a detail view in horizontal section on the line Iii-i6 of Fig. 13;

Fig. 1'7 is a detail viewin vertical section on the line i'L-l'i of Fig. 11;

Fig. 18 is a detail View on the line l8-l8 of Fig. 13;

Fig. 19 is a detail view in section of a modification also taken on the line I 4l4'of Figfll, and

Fig. 20 is a detail view in section of another form of float chamber inlet controlling valve.

Referring to the drawings by characters of reference and particularly Figs. lto 10 inclusive lindrical wall i to receive a dust collector or the like, not shown, and which defines the carburetor air inlet 8. Opposite side or end portions 9, iii of the main casing converge downward to the upper ends of the opposite end or side walls ii, 12 of the main casing. The space within the member 2 is divided internally by a vertical partition or wall I 3 into laterally positioned downward discharging bores i4, 15, each of which is in open communication at its upper end with the inlet 8. The throttle body member 3 is also provided with a vertical partition or wall l6 which aligns vertically with the wall iii to divide the member 3 into parallel, vertical, susbtantially cylindrical bores ii, 18 which together with the bores i4, i5 and the common inlet 8, define parallel, vertical, downward discharging, flow passageways through the main casing. Extending diametrically through the bores I i, I8, there is a throttle shaft l9 which is journaled at its mid-portion through the partition i6 and which projects at its opposite end portions 20, 2| through journal bearings 22, 23 respectively, in which the end portions are closely fitted to prevent leakage of air around the end portions and into the throttle bores l1, l8. Mounted on the shaft |9 there are throttle plates or valves 24, 25, preferably of the butterfly type, controlling the discharge of the explosive mixture from the outlets of the bores |1, |8 respectively, The partition I6 may be provided with a cross passage or aperture 26, establishing communication between the bores l1, l8 posterior to or on the outlet side of the throttle valves 24, 25 to aid in homogenizing the mixture and equalizing the suction in the throttle bores.

Supported by the end casing wall l6, l2 and positioned laterally thereof there is a constant level fuel reservoir or float chamber casing 21 and also a dash-pot and pump casing 26 which is positioned beneath the reservoir 21 and inclined upward to its juncture with the wall l2. The reservoir 21 is provided with a fuel inlet 29 preferably provided with astrainer 30 and leading through a valve port 3| in a valve guide member 32 into fioat chamber 33. Within the casing 21 and in chamber 33 there is a float member 34 responsive to variation in liquid level and which is supportedon one end of a float arm or lever 35 pivotally supported on a pin 36 secured in the side walls of the casing 21. The other end of lever 35 is provided with a yoke 31 received between the flanges of a collar 38 mounted on a vertically reciprocal valve 39 guided in the bore of member 32 and controlling the port 3|. Within the chamber 33 there is a partition 40 which provides a dam separating the relatively small portion or area. of chamber 33 around port 3| from the remainder of the chamber 33, the partition or dam terminating at its'upper edge slightly below the normal liquid level in chamber 33 as determined by the float 34 so that should valve 39 fail to seat, the main body of liquid fuel in chamber 33 will not drain out of the chamber, being maintained therein by partition 49 at substantially the desired constant level. The outlet 4| from chamber 33 is on the opposite side of partition 49 from port 3| and opens through the bottom wall of casing 21 into a fuel conduit 42 which extends vertically downward into the outer end portion of casing 28, see Fig. 4. The reservoir casing 21 is provided with a cover or closure member 43 which is sealed by a gasket 44 to the top edge of the fioat chamber casing wall 45 to prevent leakage or uncontrolled admission of air into the chamber 33 above the liquid therein, the cover being tightly fixed in position by screws 46.

The inside face of wall within the bores |4, I5 is straight to form flat, vertical, internal wall surfaces 41, 48 in a common plane, the surfaces 41, .48 being provided with a horizontal, shallow, segmental recess 49 adjacent their upper ends to receive the circumferential edge portion of a shaft 50 which extends through or across the bores l4 and I5 and through a close fitting aperture 5| in the wall |3. The ends of the shaft 50 are journaled in cylindrical bores 52, 53 formed in the side walls of the member 2. The outer ends of the bores 52, 53 are closed and sealed by plug members 54. The inside walls of bores I4, l5 opposite the wall I I and adjacent the reservoir casing 21 are preferably substantially semi-circular in horizontal cross-section, as at 55, 56. Within each of the bores |4, I5 and rigidly fixed to the shaft 59, there are valve members 51, 58 which are responsive to suction and which control the admission of air from the inlet 6 to the mixing chambers 59, 66 in bores l4, IS. The valve members 51. 58 are preferably secured to the shaft 50 by screws 6| and extend in a downward inclined direction at an angle of substantially 30, for example, to the horizontal and toward the curved walls 55, 56, the valve members being similarly curved at their free end edges to conform to and seat against the curved wall surface. The valve members 51, 58 closely flt the bores l4, l5 so as to prevent leakage of air therepast into the mixing chambers.

In the casing wall l2 are a pair of laterally spaced, vertical bores 62, 63 which open at their upper ends into the air inlet 8 through the top face of a horizontal shoulder 64 formed in the upper portion of wall l2. The bores 62, 63 extend vertically downward to a point below the air valves 51, 58 and thence extend at a downward inclination and inwardly to the mixing chambers 59, 60 respectively, opening thereinto radially through the curved walls 55, 56, see Fig. 8. In the mixing chamber outlet end portions of the bores 62, 63 there are rigidly secured projecting mixture discharge nozzle members 65, 66 having cylindrical bores therethrough and preferably being externally rectangular in transverse cross-section. The discharge orifice 61 of each nozzle member opens through a nozzle end face which is inclined to the longitudinal axes of the nozzle members, providing a beveled nozzle end portion having an extended side wall 68 on each nozzle member which is directed toward the partition l3, which nozzle construction acts to enhance the even distribution of the mixture discharged from the nozzle members. In and tightly fitting the vertical portions of bores 62, 63 there are tubes 69, 19, see Fig. 1, which are of a general Venturi type and of identical construction and therefore a description of tube 69 will suflice for both. The tube 69 has a converging inlet bore portion 1| and a diverging outlet bore portion 12, which portions are joined at the throat of the tube by an annular shoulder 13 facing the diverging portion 12. The tube 69 has in its upper end portion vertically spaced, circumferential recesses which define with the wall of bore 62 upper and lower annular chambers 14, 15 respectively, which are separated by a circumferential, annular shoulder or flange 16 which fits the bore 62. The taper of the converging bore portion 1| is preferably formed with a 22 included angle and the taper of the diverging portion 12 is preferably formed with a 7 included angle so that the tube 69 is substantially of Venturi tube form but is modified by the downward facing shoulder 13 at its throat. The tube 69 has a plurality of fuel discharge passages or ports 11 having their inlet ends circumferentially spaced about the annular chamber 14 and opening therefrom in downward converging relation into the diverging bore portion 12 at the throat of the tube 69 and just below or at the shoulder 13. Also opening into the diverging bore portion 12 there are one or more ports or passages 18 having their inlet ends opening from the annular chamber 15 and extending in an upward inclined direction with their outlet en'ds opening or discharging at the throat of tube 69 in the same plane transverse to the longitudinal axis of the tube as are the outlets of ports 11 and therefore directly below or at the shoulder 13, the outlet or discharge ends of the ports 11 and 18 being equally spaced from the shoulder 13 so that the ports 11, 18 will be subject equally to any variations of pressure in the bore of tube 69. The increased diameter of the tube throat resulting from shoulder I9 prevents restriction of the throat by the fuel discharging thereinto through ports 11 and'maintains the suction on ports 1! and I8 substantially the same as the throat suction would be if no fuel were admitted thereto, thereby increasing the suction or decreasing the pressure on ports II and I8 relative to the suction or pressure which would be obtained if shoulder 13 were not employed.

Also in the wall I2 and preferably between the bores 82, 68 and the reservoir casing 2I, there is a vertical fuel conduit 19 which branches at its upper end to feed fuel to the annular chambers I9 of the tubes 99, 19, these chambers communicating with conduit I9 through the branchconduits 89, 8i, see Fig. 1. Extending into the wall ,I2 there is a horizontal, cylindrical bore 82 which intersects the conduit I9 and which is closed at its inner end by an end wall83, the bore 82 at its intersection with. the conduit I9 forming a valve chamber and being of greater diameter than the diameter of conduit I9. In the bore or chamber 82 there is a cylindrical, rotatable valve member 84 which when in its position most restricting the conduit I9 has on its underside a substantially segmental-cross slot of a width substantially equal to the diameter of conduit I9. The remaining segmental portion 88 is cut away at its opposite side edges to provide ports 81, 88 which register with the conduit I9 and which act as the valve member is rotated to regulate and permit an increasing flow through the conduit I9. The valve member 89 has, a stem'89 which extends externally of the wall I2 and through a packing recess 99 formed as an enlargement of and at the outer end portion of bore 82. In the recess 99 and surrounding stem or shaft 89 is packing mate- ,rial 9I positioned between cone-shaped metal end of the stem or shaft 89 is a crank or lever arm 95 which is adjustably fixed thereto. Mounted on the free end of the arm 95 there is an eccentric 99 comprising eccentrically joined pins 91, 98 of which pin 91 extends through an aperture in arm 95 to be locked in adjusted position by the nut 99. The projecting pin 99 forms a connecting arm on the lever 95 and has pivotally secured thereto one end of a connecting link or member I99. The other end of link I99 is pivotally secured to an arm I9! rigid with the throttle operating lever I92 which is rigidly fixed on the projecting end portion 2I of the throttle shaft. The throttle lever I92 also has rigid therewith an arm I93 which extends upwardly when the throttle valves are in closed position. The arm I93 carries an adjustable stop member or screw I99 cooperable with an abutment or flange I95 projecting from the throttle body member 8 to regulate or limit the extent of closing movement of the throttle valves, the members I94, I95 forming the throttle valve idle adjustment. On the other projecting end portion 29 of the throttle shaft there is journaled for rotation relative thereto an operating lever- I99 having an arm I9I cooperable with an abutment member I98 fixed on the shaft end portion 29.

- The arm I91 and the abutment member I98 cooperate on clockwise rotation of-arm I96, fac ing Fig. 4, to move the throttle valves toward open position and limit closing movement of Positioned at one side of the vertical tube re ceiving 'bore 63 and in the wall i2,'there is an air supply passage or duct I99 which is closed at its top end by a plug H9 and which has an air inlet port III adjacent its upper end, the port being downward inclined for dirt elimination and I opening into the common air inlet 8. The duct I99 opens at its opposite end at an upward inclination into the float chamber 33 adjacent the cover member 43. Screw-threaded or otherwise sealed in the outlet end portion III! of duct I99 is a plug member II3 having a calibrated air flow controlling port II4 to regulate the admission of atmospheric air from inlet 8 to the interior of the float chamber above the liquid level therein. The plug member II3, which is hollow, projects from the wall of the chamber 33 and terminates well above the liquid level.

Within the dash-pot and pump casing 28 there is a cylindrical housing member I I5 which is longitudinally "reciprocal therein. The housing member II5 is internally cylindrical to receive a piston I I9 which is preferably substantiallycupshaped, having a cylindrical side wall portion I II fitting the bore of housing member II5 and cooperating therewith to guide the piston H6. The housing member has an end wall II8 opposite the piston H9 and toward which the,piston'" moves upon its compression stroke. Through the end wall I I8 there are a plurality of ports I I9 establishing communication between the chamber I29 within the housing and the portion of the chamber I2I on the opposite side of wall II9. Within the chamber I 29 there is a helical coil spring I 22 which at its opposite ends abuts theinside face of the end wall H8 and the inside face of piston IIG, being held under compression therebetween to normally urge the piston to the position shown in Fig. 4 and through its suction stroke. The chamber I 29 is annular in cross-section, having its inner cylindrical wall formed by a tubular member or sleeve I23 which projects concentrically from wall H8 and by a tubular member I29 which slidably fits within the member I 29. The member I29 extends through a central aperture I25 in the-piston IIS and is provided'with a circumferential end flange I28 which abuts the outside face of piston I I 9, the piston being held against flange I28 by spring I22 so that the member I24 and the piston H6 are movable in unison. The casing 28 is preferably provided with a cover member I2I which is removably secured in position by screws I28, a gasket I 29 being provided to seal the joint. Extending diagonally through the main casing and the partition wall I3 at an angle of' by screws I43 substantially 45", there is a guide bore I30 which is concentric with the bore of casing 28 and which opens thereinto at its lower end. The lower end portion of bore I30 is of enlarged diameter, as at I3I, the enlarged bore portion being provided with a cylindrical flange extension I32 which projects into chamber I2I. The enlarged bore portion I3I intersects and communicates with the conduit 19 below or on the inlet side of the metering valve 84. Projecting concentrically from the outside face of wall II8, there is a tubular member or sleeve I33 which is reciprocal in the enlarged bore portion I 3I and which has an end wall I34 having a central fuel port I35 therethrough. The tubular member I33 is preferably provided with a circumferential recess containing suitable packing material I36 to prevent passage of fuel through bore I3I around the member I33. The upper end of bore I30 opens into a vertical, substantially rectangular recess or chamber I31 formed or opening into the partition I3. Longitudinally reciprocal in the bore I30 is a rod I38 which extends at its upper end into chamber I31 and at its lower end through a central aperture I39 in a ported spider I40 within and rigid with the tubular member I24 and preferably formed integrally therewith. The rod I38 is held in engagement with the member I24 by a cross pin I4I passed through the rod and engaging the under or inlet side of the spider I40.

The upper end of rod I38 is connected to an arm or crank member I42 positioned in chamber I31 and rigid with and projecting from shaft 50. A link I43 pivotally secured at its opposite ends to the arm I42 and the rod I38 operatively connects the same so that the air valves 51, 58 are operatively connected to the piston II6, the air valves normally being urged toward closed position by the force of spring I22. The chamber I31 is closed and sealed by a cap or cover member I43 which is secured and sealed to the main casing The portion of the rod I38 intermediate its ends and which extends through port I35 comprises a fuel metering valve defined by the tapered portion I44. The portion I44 may have a plurality of different tapers to enhance the control of the fuel flowing through port I35. It is to be noted that the annular orifice surrounding valve I44 and defined by port I35 is never closed as this would prevent supply of fuel to the mixing chamber. The chamber I2I in casing 28 is in communication at its uppermost point with the float chamber below the liquid level therein by means of a bleed passage I45 which is calibrated and of minute cross-section, preferably of such small size that substantially no fuel will be discharged therethrough under piston compression into the float chamber, the bleed passage functioning to relieve the chamber of gas or air bubbles which might trap therein. The housing member II has an external tooth rack I46 extending longitudinally thereof. The rack teeth preferably extend completely around the housing member H5 so that the rack can not become disengaged from the teeth of pinion I41 with which it meshes. The pinion I41 is rigidly fixed on an operating shaft I48, preferably being formed integral therewith and is positioned in a bore I49 extending horizontally into the casing wall which separates the interiors of the reservoir casing 21 and the pump casing 28. The shaft I48 is journaled at its inner end in the closed end of the bore, as at I50, and at its outer end is journaled in the packing nut I5I which closes the bore I49. The portion of the bore I49 containing pinion I41 is sealed against leakage of air thereinto from atmosphere by packing material I52 positioned between oppositely directed conical metal plates I53 and held under compression by a helical coil spring I54 positioned between the nut I5I and the packing material. The nut I5I has a cylindrical extension I55 on which is journaled for rotation an operating lever I55, the lever preferably being held axially in position by a U-shaped locking member I56, for example. Rigid with the lever I 56 there is an arm I51 which carries an adjustment screw I58 which forms a stop for engagement by a lug or stop member I59 carried by a sleeve I60 rigidly secured on the external projecting end of shaft I48. The lug I59 and stop screw I58 are normally urged into engagement with each other by a coil spring I6I which surrounds the extension I55 and has one end anchored to the lever I56 and its other end anchored to the shaft I48, preferably by engagement with the lug I59. The lever I56 is provided with a fiat plate portion I62 having its marginal edge or face I63 forming an eccentric cam surface. At the ends of the surface I63 there are stop lugs I64, I65 which limit rotation of lever I56 and therefore of shaft I48 and which engage a stop member I66 projecting fromthe pump casing 28. The stop member I66 is provided with a guide aperture I61 aligned with the cam face I63 and through which one end of a thrust rod I68 extends for engagement with the cam face I63. The other end portion of the rod I68 is guided in an apertured lug or ear I69 projecting from the casing flange 4 in overlying relation to the idling abutment stop I05. The rod I68 is held in engagement with the cam face I63 by a helical coil spring I surrounding the rod and fixed thereto at one end, as at HI, and having its other end engaging the ear I69. The throttle lever arm I03 extends, upward into opposing relation to the free end I12 of rod I68 and carries an adjustable abutment screw I13 cooperable with the rod end I12 and engageable thereby upon operation of the rod I68 by the cam face I63 to move the throttle valves toward open position.

The annular chambers in the bores 62, 63 are in communication with the fioat chamber 33 above the liquid level therein by means of conduits I14, I15 respectively, which have their inlet ends defined by tubular members I16, I11 respectively, which extend at an upward inclination through the float chamber wall and to a point closelyadjacent the float chamber cover member 43 to prevent the ingress of fuel to the conduits I14, I15. The conduits I14, I15 are each'in communication with the pump chamber I by means of the conduits I18, I19 which have verticallyextending portions opening downward and through the top wall of chamber I2I on opposite sides of the bleed passage I45, see Figs. 4, '7 and 9. As the conduits I18, I19 are of identical construction, the conduit I18 alone is shown in vertical longitudinal section in Fig. 7. Within the vertical portions of each of the conduits I18, I19 there is a valve chamber I80 containing a check valve I8I preferably of the ball type, having a horizontal seat and only sufficiently heavy to prevent withdrawal of fuel from the chamber I2I by suction in the throats of tubes 69 and 10 respectively. The valves I8I serve to close the conduits I18, I19 upon the downward return or suction stroke of piston II6 to prevent the indrawing of air or gas to the pump chamber and to insure the filling of the pump chamber with 2,061,494. liquid fuel which enters the same through the piston clearance around wall ill. .The conduits I118, I119 are preferably turned at the chambers E80 above the valves i8I to align with and open into the conduits I'M, M5. The portions of conduits H8, 919 between chambers i180 and conduits H0, 675, respectively, are restricted by callbrated bores lBI which are of sufliciently large diameter to permit an adequate pump discharge therethrough and which serve in conjunction with the flow areas of conduits I10, M5 to prevent the suction on ports F8 from drawing fuel from the pump chamber into conduits H4, H5. The restricted bores I8I also serve to increase the rapidity of discharge from the pump at the point where the discharging fuel meets and joins the air stream in conduits I'M, H5. Stop members I82 are preferably provided to limit the lift of the valves WI and preferably comprise pins carried by and depending from screws 583 which are screw-threaded into the top ends of the vertical portions of bores E18, M0. The main fuel conduit is provided with a bleed hole I84 through the end wall i I8, see Fig. 4, and establishing communication between the interior of the tubular member H23 and the chamber BZI so that any trapped air or gas bubbles can escape from the main fuel conduit into chamber HI and thence through bleed passage M5. 4 n

The mixing, chambers 59, are also preferably in communication with each other through a horizontal slot I85 anterior to the throttle valves 624, M to equalize the sub-atmospheric pressures in the mixing chambers and acting on the discharge nozzles 65, 88.

In a carburetor such as the one illustrated in Figs. 1 to inclusive, I have found it desirable and that the carburetor will operate eiflciently when the following dimensional sizes are utilized; but the sizes given are to be taken merely as illustrative and are not, as will be obvious, tor be considered as limiting or circumscribing the scope of the claims. It is preferable that in each tube, one air suction port I8 be used having a diameter of .043" but a plurality of such ports I8 may be employed in each tube having the sum total of their cross-sectional areas equivalent to .043". Preferably six ports H are provided in each tube for supplying fuel to the bypass passageway, each such port having a diameter of .059". The throat between the converging-diverging bores 'II, I2 is preferably 54;", with the shoulder I3 increasing the size at the throat to a?" diameter. The diameter of the fuel passage or conduit I8 is preferably diameter. The main fuel port or orifice I35 preferably has a diameter of .171" and the taper of the metering valve I 44 may generally be considered as a taper of substantially /g" per foot. The economizer valve 84 acts to control fuel flow through passage I9 and to decrease the flow permitted by metering valve I between say 25 miles per hour and 65 miles per hour level road car speeds by from two to three pints of gasoline per hour. When the carburetor serves as the agency or means for lifting fuel from a lower level tank or source of supply to the float chamber 33, the calibrated air inlet port I is preferably of a diameter of .041 which results in the maintenance of a vacuum or sub-atmospheric pressure above the liquid level in the float chamber sumcient to raise fuel from the low level supply tank by suction and to maintain a substantially constant pressurediiferential of 9" of gasoline between the pressure acting on the surface of the gasoline in reservoir '33 and the pressure or vacuum transmitted through conduit I9 and serving to-draw fuel" or gasoline from the, reservoir 33 to the mixing chambers. The diameter of bleed passage I45 is preferably -.042" and the diameter of bleed port I84 is also preferably .042". The piston side wall II'I preferably has a mean diametral clearance in the bore of housing member N5 of .0025". The metering rod I38 is preferably in diameter and has a longitudinal travel of on full movement of the air valves, the tapered metering valve I 44 being preferably set so that when the air valves are in closed position it will be substantially in longitudinal movement from engagement or seating in the orifice I35. The housing member H5 has A" longitudinal movement on full movement of .lever I56. Theforce exerted by dash-pot spring I22 when the parts are in the positions shown is suflicient to hold the air valves 51, 58 closed against a vacuum in the mixing chambers corresponding to 24" of gasoline. The pump discharge ducts I18, I19 are each 5 2": in diameter and are each restricted by bores I 8I to a diameter of .046". The bores of tubes 6, ill are each a in diameter. The float chamber inlet port 3| is 3 2'" in diameter. The nozzle members 85, 66 have bores of diameter, and at the base of the inclined orifice. face are square in transverse cross-section. The pressure equalizing slot or opening I85 is wide and 3%" deep,the slot 26 being wide and deep. .The effective flow areas of economizer valve ports 81 and 88 are respectively slightly less than .001 square inch and .004 square inch when the valve 84 is in engine idling position, Fig. 10, the diameter of valve 84 being A helical coil spring. I36 is preferably positioned in the casing 28 and held under compression between the cover member I21 and the lower end of the housing member I I 5 in order to take up any lost motion between the rack I46 and pinion I41 thereby insuring the maintaining of the orifice I35 in a given position for a given setting of the lever arm I 58.

The operation of the carburetor above described is as follows, the casing'I having been secured by flange 3 and sealed to a duplex engine-intake manifold and the float chamber inlet 23 having been connected by a suitable conduit to a low level source of fuel supply or main tank. The main fuel orifice I35 is adjusted or set for warm engine idling operation relative to valve I44 bymeans of adjustment screw I58 without changing thereby the normal position, Fig. 2, of lever I56. The throttle valveswill also be set or adjusted for warm engine idling operation and the economizer valve will be set or adjusted to start restricting the main fuel supply at about 25 miles per hour level road car speed.- With. the parts in the positions shown, the lever I56 is rotated counterclockwise, facing Fig. 2, which lever will be rotated until stop I65 engages stopv member I66. The downward movement of hous ing member II5 by operation of .lever I56 moves the sleeve member I33 relative to valve I 44 to increase the size of the annular fuel orifice through port I35, thereby to increase the ratio of fuel to air supplied to the mixing chambers and to provide an enriched mixture for engine starting. This movement of housing member II5 also compresses spring I22 thereby increasing the load on or resistance to opening movement of the air valves 51, 56, holding them closed. and sealed against the suction in the mixing chambers. In addition, the cam face I63 moves the thrust rod I68 longitudinally against the force of the lightreturn spring I10 and pushes on the adjustable abutment screw I 13 to rotate or move the throttle valves 24, 25 toward open position, the extent of opening movement of the throttle valves being determined by the adjustment of screw I13 and the throttle valves being sufflciently opened when stop I65 engages stop I66 to maintain warm engine operation at a high idling speed equivalent to say 15 miles per hour level road car speed. Movement of throttle arm I03 by rod I68 also moves the throttle arm IOI which is connected to the economizer valve 84 but the movement is insufficient to change the effective flow area through conduit 19 as the extent of closing movement of economizer valve port 88 is fully compensated by the opening movement of economizer valve port 81, the port or slot 88 not being fully closed by this movement of the throttle valves. If the engine is now cranked for starting, the sub-atmospheric pressure created thereby in the mixing chambers 59, 60 will be insufficient even with the lever arm I56 in its normal warm engine operating position, as in Fig. 10, to cause opening movement of the air valves 51, 58 but air entering the main inlet 8 will by-pass the air valves by means of the passageways through the tubes 69, 10. The air passing the throats of tubes 69, 10 will create suction on the fuel ports 11 and the air lift or suction ports 18. The suction on ports 11 will be transmitted to annular chamber I4 and thence to conduit 19 through the communicating branch conduits 80, 8|. Liquid fuel .will therefore be drawn from reservoir or chamber 33 through conduit 42, chamber I2I, tubular members I24, I23 and I33, and the more widely opened fuel orifice I35 into conduit 19 and thence through ports 11 into the throats of tubes 69, Ill, the economizer valve 84 not restricting the flow of the fuel which has been permitted to flow through the orifice I35. The suction at the throats of tubes 69, 10 acting on ports 18 acts through conduits I14, I15 and their respective tubes I16, I11 to withdraw vapor of the liquid fuel and air from the float chamber 33 above the liquid level therein thereby creating a sub-atmospheric pressure on the liquid inthe float chamber, which suction is not satisfied by the air admitted through calibrated port II4 to the float chamber and thence to withdrawal conduits I14, I15. By inclining the passages or ports 18 as above described toward the tube air inlet end, I have found by manometer test that sudden changes of pressure at the tube throat are not as quickly transmitted to the float chamber air space as when the longit .lnal axis of the ports are normal or at right angles to the longitudinal axis of the tube and by manometer, dynamometer and road test that the sudden inrush of air into the carburetor due to automatic excess opening of the.

suction responsive valves on quick opening of the throttle or when the throttle is kicked open is compensated for by the concurrent and momentary increase in the pressure differential acting on the fuel in the float chamber. The air entering the float chamber through port H4 and tube H3 serves due to the spacing of tube II3 from the tubes I16, I11, to sweep continuously from the chamber above the liquid level the gas or vapor of the liquid fuel and causes discharge of the gas or vapor through tubes I16, I11 into the Venturi type tubes 69, 11. The air entering tubes 69, 10 from main inlet 8 mixes at the throats of the tubes and below the shoulders 13 with the liquid fuel supplied thereto through ports I1, the rich mixture thus formed discharging at a downward inclination through the nozzle members 65, 66 into the mixing chambers 59, 60. The sub atmospheric pressure created in the float chamber above the liquid level therein by the suction at the throats of tubes 69, 10 draws fuel from the low level main tank through inlet 29 into the chamber 33 upon lowering of float 34 which opens the float controlled valve 39 thereby replenishing the fuel withdrawn from chamber 33 and maintaining the liquid level therein constant at the line L-L. The depression or vacuum at engine idling speeds with the parts positioned as in Fig. 10 and dimensioned as above set forth will be substantially equal to 40" of gasoline over the liquid in the float chamber. Upon operation of the engine under its own power and as the engine warms up, the lever I56 will be returned from its starting position and in a clockwise direction, facing Fig. 2, toward the warm engine operating position thereof shown in Fig. 2 so as to decrease the ratio of fuel to air discharging to the engine from the mixing chambers. The extent of return movement of lever I56 will be readily determined by the operator in accordance with resulting engine performance, the return movement, as will be obvious, decreasing the added resistance to opening movement of or load on the air valves 51, 58 by spring I22, decreasing the temporarily increased effective flow area through main fuel orifice I35 and also permitting movement of the throttle valves toward normal warm engine idling position. With lever I56 in any position wherein stop I64 is out of engagement with stop I66 the ratio of fuel to air supplied to the engine will be increased for all engine speeds. When the engine has been completely warmed up, the lever I56 will have been returned to the position shown in Fig. 2 when the remaining parts and mechanism of the carburetor will be in the positions shown in the drawings at engine idling speeds.

mixing chambers will cause opening movement of the air valves 51, 58, their positions being determined by the quantity of air flowing therepast into the mixing chambers and being such as to maintain the sub-atmospheric pressures in the mixing chambers within predetermined limits and substantially constant. The opening movement of the air valves 51, 58 rotates shaft 50 counter-clockwise, facing Fig. 4, to move or pull rod I38 upward and metering valve I44 in an opening direction or away from its'oriflce I35 to increase the quantity of fuel supplied to the conduit 19 and the mixing chambers to maintain the desired fuel-air ratio in accordance with the opening movement of the air valves 51, 58. As above noted, the economizer valve 84 does not act below a position of the throttle valves corresponding to say 25 miles per hour level road car speed to restrict or cut down the quantity of fuel supplied through orifice I35 but as the throttle valves are moved further open to further increase the engine speed, the economizer valve 80 limits the fuel which has passed through oriflce 635 as the valves EM and 9t simultaneously move toward further open positions. The fuel flowing through orifice I35 will be limited or restricted by the economizer-valve 84 at level road loads until the economizer valve 84 has been moved to a position by operation of the throttle valves corresponding to a throttle valve open position of substantially miles per hour level road car speed. Above 65 miles per hour level road car speed, the economizer valve 82 no longer restricts the fuel which is supplied through oriflee I35 so that the ratio of fuel to air supplied to the mixing chambers is then solely under control of the metering valve SM.

The operation of the air valves 51, 58 is controlled by'the spring I22 and the dash-pot and pump piston H6 which serve to steady the movement of the air valves and to prevent fluctuating operation thereof, the spring I22 also serving. to move the air valves toward closed position upon increase of pressure in the mixing chambers whether caused by increasedload on the engine or movement of the throttle valves toward closed position. During full load, wide open throttle operation of the engine, the economizer valve 90 will be in wide open position, permitting substantially unrestricted flow through conduit l9 and therefore the metering valve I42 will be in complete control of the, fuel supplied to the mixing chambers as determined by and in accordance with the position of the air valves 51, 58.

Upon quick opening movement of the throttle valves 2%, 25 for rapid acceleration of the engine, the sudden decrease in pressure in the mixing chambers will cause air valves 51, 58 likewise to move quickly in an opening direction causing operation of the piston M6 to compress fuel in the bore of housing member H5. The fuel under pressure will be discharged by piston I I6 through ports, M9 in the housing member wall H8 and thence upwardly through conduits I18, I19, lifting ball checks I8I and discharging thence into and through conduits I14, I15 and their outlet ports 18 into the throats of tubes 69, 10, thereby augmenting or supplementing the fuel supplied to the mixing chambers through conduit I9. Some of the fuel so discharged may pass into the tubes I16, I11 if the discharge from the pump chamber is sufficiently rapid and will be discharged by the air entering the tubes I16, I11 through ports 18 upon cessation of the piston movement. The bleed passages I45 and I84 are relatively so small that substantially no fuel is discharged therethrough on the pump discharge stroke, substantially all of the fuel passing up into and through the conduits I18, I19. The operation of the pump piston will not affect the discharge of fuel through the main fuel discharge conduit as the main conduit which opens from the float chamber through opening 4| extends concentrically through the pump chamber and is separated therefrom by the tubular members I24, I23 and I33 which form a partition or cylindrical wall separating the conduit from the pump chamber.

The carburetor shown in Figs. 11 to 18 inclusive is similar in many respects to the carburetor above described and shown in Figs. 1 to 10 inclusive and therefore the primes of the reference, characters applied to Figs. 1 to 10 inclusive willbe employed to designate the same parts of the carburetor of Figs. 11 to 18. This carburetor of Figs. 11 to 18 inclusive'will now be described and differs from the carburetor of'Figs. 1 to 10 inclusive in the following respects: Instead of employing a separate by-pass passageway for bypassing each of the air valves, a passageway having a common inlet and a branched outlet is employed. This passageway comprises a single vertical bore I87 containing a Venturi type tube I88 substantially similar to the tubes E39, 10, save that it is screw-threaded, as at i89,'into the threaded upper end portion of the bore of passageway N31. The vertical portion I87 of the by-pass passagewayopens at its lower end into a transverse horizontal passageway portion I90 which is vertically below the closed position of the air valves and which is positioned laterally of the mixing chambers 59, 60'. The passageway portion I90 comprises-a manifold defining passageway branches having from its opposite end portions downward inclined bores opening into the -mixing chambers 59', t0 and in these bores are hollow nozzle members I9 I, E92 which project into the mixing chamber bores I5 and M respectively. The annular chamber I8 in the tube 598 is in communication with the float chamber 33' above the liquid level therein by means of a conduit 093. The upper end of fuel conduit l9 opens through a single port I 90 into the annular fuel chamber I4. The economizer valve 84 shown in detail in Fig. 16 functions to obtain the same result as valve 84 but is provided with a transverse passage .I95 having a diameter equal to the diameter of conduit l9 and which is movable into registry therewith in the full open position of valve 8 5. The upper and lower segmental portions of valve 841 are provided with upper and lower radial slots I96, I91 which provide a mini- I mum flow through the conduit I9 and which meter the flowthrough saidconduit as the valve is moved in clockwise direction, facing Fig. 13, on opening movement of the throttle valves. The housing member H5 does not have any ports in its end wall I I8, the pump discharge being through the orifice I35 and the conduit I9. In

the bore of housing member 8 I5 there is a piston I98.which has ports I99 therethrough establishing communicationbetween the interior of the dash-pot and pump casing 28' and the interior of the housing member H5. The ports I99 are controlled by a check valve 200, preferably a flat circular disc, retained in operative position by a ,spider 20 I. The spider 20I is held in engagement chamber in this carburetor being a cup-like membar 203 surrounding the valve guide member 32' and clamped in position thereby, as at 204. The air inlet to the top of the float chamber from the main air inlet 8' isthrough a duct 205 having in its inlet end a calibrated plug 206 having there through the calibrated orifice III, see Fig. 15. The throttle lever I 02 which is fixed on the throttle shaft end portion 2| has an adjustable abutment screw 20'! which engages a transverse flange or arm 208 on an operating link 209 which is.journaled on the throttle shaft end portion 2| and positioned betweenthe lever I02 and the throttle body 3'. The flange 208 is movable into engagement with a lug or ear 2I0 on the throttle body member 3, to limit closing movement of the throttle valves 24, 25. The other end of the link 209 is slotted, as at 2I I,'to provide a lostmotion connection with the pinion operating lever I56. Through the slot 2 II there is a screw 2I2 which is eccentric to the pinion shaft I48 and which secures the link 209 to the lever I56. The lever I56 has an arm 2I3 carrying an adjustable abutment screw 2I4 engageable with a stop 2I5 on the casing 28'. The arm 2I3 is provided with a longitudinal recess which intersects the transverse threaded bore carrying the screw 2I4. In the longitudinal recess there is a detent member or dog 2I6 normally urged into engagement with the screw 2I4-by a light coil backing spring, the detent 2I6 cooperating with longitudinal slots or grooves 2II in the screw 2I4 to hold or look the screw in adjusted position. The lever I56 is normally held rigid with shaft I48 by a clamping screw 2IB, the lever I56 being adjustable about shaft I48 to regulate the position of the lever I56 relative to pinion I41 and the throttle valves. The throttle lever I02 is operatively connected to the economizer valve lever or crank by a link 2I9 which is temperature responsive and preferably of bimetal having a loop or bowed portion 220 to multiply the longitudinal expansion or contraction of the link upon temperature change. The link 2I9 expands upon decrease of temperature and therefore moves the economizer valve 84 toward open position without disturbing the setting of the throttle valves with the result that the economizer valve 84 permits a greater flow of fuel, the flow permitted increasing with decrease of temperature thereby causing an increase in the ratio of fuel to air and the supply of a richer fuel mixture to the engine at level road car speeds between 25 and 65 miles per hour.

The sizes of the ports and passageways and of the other parts of this carburetor are preferably the same as like ports and parts described above in connection with Figs. 1 to 10 inclusive. The operation of this carburetor will be clear to those skilled in the art from the detailed description of operation of the carburetor of Figs. 1 to 10 inclusive, taken with the foregoing description of differences of this carburetor with respect to the carburetor of Figs. 1 to 10 inclusive. However, it may be noted that the main fuel supply is augmented or supplemented on the pump discharge by additional fuel supplied through the main conduit I9. Since the economizer valve 84' is operated upon operation of the throttle valvesand the movement of the piston I98 results from opening of the air valves 51, 58, it will be apparent that'the economizer valve 84 does not obstruct the discharge of fuel by the pump piston.

In Fig. 19, I have shown a modification of the dash-pot and pump structure contained in the casing 28. In this form, the reciprocal housing 22I which is substantially similar in form to housing member H5 is closed and sealed at its lower end by an end wall or plug 222. Within the bore of housing member 22I there is a piston 223 which is secured to the endof metering valve rod I38 and which cooperates with the air valve resisting spring I22, as described above. The housing member 22I is at its upper end portion adjacent conduit I9 of less diameter than the bore of ca'sing 28 so as to provide an annular passageway 224 for supplying fuel from the float chamber 33' to the conduit I9. The end wall 225 of member 22I opposite the plug member 222 and corresponding to end wall II8, Fig. 14, is provided with a plurality of valve ports or apertures 226 which are controlled by a flat disc check valve 221. The disc valve 221 may be of a stiff, light fabric impervious to liquid, and be held in a valve cage or 5 retaining member 228. The end of spring I22 opposite piston 223 preferably abuts a flange on the cage 228 to hold the same in engagement with the end wall 225 and in fixed position in the housing member 22I. The fuel fed from the float chamber 33 and passing through annular passageway 224 passes substantially directly from ports 226 into the tubular member I33 for supply to conduit I9. On sudden opening movement of the air valves connected to rod I38 the fuel under pressure by piston 223 forces valve 221 to its seat, closing the ports 226 and discharging through orifice I35 to supplement or au ment the normal fuel discharge through conduit I9.

The float chamber inlet controlling valve shown in Fig. 20 may be used in lieu of the inlet valves above described. In the float chamber inlet passage 29 there is a ported guide member 229 having a vertical bore 230 therethrough to receive the reciprocal valve operating member or stem 23I carrying at its upper end the flanged collar 38 cooperating with the float actuated lever 35. The lower end portion of the guide member bore 230 is of enlarged diameter to receive a ported valve seat member 232 which is rigidly fixed in the bore as by a press flt. The inlet port 233 through member 232 is controlled by a check valve 234, preferably a flat disc, which seats on an annular rib or bead seat on the top face of member 3 232 and surrounding port 233. The valve 234 is separate from stem 23I, so that it can seat independently of the action of stem 23I. The valve 234 is normally moved to its seat by float 34 acting through stem 23I when the liquid level reaches line LL thereby maintaining a constant liquid level in chamber 33 and is also closed irrespective of float operation when the fluid pressure in chamber 33 exceeds the pressure in the inlet 29 thereby preventing liquid fuel in the main supply line to inlet 29 from draining back into the main lower level supply tank. The valve 234 will open when the liquid level drops below line LL,

if the pressure in inlet 29 exceeds the pressure acting on the chamber or outlet side of the valve 50 which is the case during operation or rumiing of the engine.

Although I have described the carburetors embodying my invention as particularly adapted and constructed for drawing or lifting fuel from 5 a low level supply tank to the carburetor float chamber, I have found these carburetors are equally operable to supply a proper mixture of air and fuel to an internal combustion engine when the float chamber is supplied with fuel by an auxiliary pump or other independent supply means. However, I have found that these carburetors when utilized with an independent passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air to said .mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a bore portion of restricted cross-sectional fiow area, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, said conduit being sealed against admission of air and having a portion of its length above the liquid level in said reservoir, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said bore portion, said outlets being positioned in a common plane normal to the longitudinal axis of said bore portion whereby said conduits are subjected equally to variations in pressure in said bore portion, and means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will be discharged into said bore portion and through said second-named passageway into said mixing chamber.

2. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a pasageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a bore portion of restricted cross-sectional flow area, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, said conduit being sealed against admission of air and having a portion of its length above the liquid level in said reservoir, an air and vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said bore portion, said outlets being positioned in a common plane normal to'the longitudinal axis of said bore portion whereby said conduits are subjected equally to variations in pressure in said bore portion, and means to supply air to said reservoir above the liquid level therein at a point spaced from the inlet to said second-named conduit whereby the supplied air will sweep the interior of said reservoir above the liquid level and will maintain over the liquid a greater pressure than exists in said fuel conduit.

3. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling admission of air to said mixing chamber and operable to maintain the subatmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a converging bore portion and a diverging mixture discharge bore portion, an annular shoulder joining said bore portions and facing said diverging portion, a liquid fuel reservoir, a fuel supply conduit leading from said: reservoir below the liquid level therein and having an outlet at and discharging into said second-named pasageway, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said second-named passageway, said conduit outlets being positioned closely adjacent to and substantially equally spaced from said shoulder and between said shoulder and said mixing chamber, and means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will be discharged into said second-named passageway and thence into said mixing chamber.

4. A carburetor comprising a casing having a passageway therethrough including a downward discharging mixing chamber having an air inlet in alignment therewith, suction responsive means pivotally supported for downward swinging movement and controlling admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a downward extending passageway having an air inlet and discharging laterally into said mixing chamber, an extension for the discharge end of said secondnamed passageway spacing the outlet of said second-named passageway from the walls of said mixing chamber, said second-named passag ay having a converging bore portion and a diverging mixture discharge bore portion, an annular shoulder joining said bore portions and facing said diverging portion, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging laterally into said diverging portion, a vapor withdrawal conduit therein and having an outlet discharging laterally into said diverging portion, said conduit outlets being positioned closely adjacent to and substan tially equally spaced from said shoulder, and means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will be discharged into said second-named passageway and thence into said mixing chamber.

5. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a bore portion ofrestricted cross-sectional flow area, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, said conduit being sealed against admission of air and having a portion of its length above the'liquid level in said reservoir, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said bore portion, said outlets opening laterally through the side wall of said bore portion and being positioned in a common plane normal to the longitudinal axis of said bore portion whereby said conduits are subjected equally to variations in pressure in said bore portion, and means to means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a bore portion of restricted cross-sectional flow area, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, said conduit having a portion of its length extending above the liquid level in said reservoir, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said bore portion, said outlets being positioned in a common plane normal to the longitudinal axis of said bore portion whereby said conduits are subjected equally to variations in pressure in said bore portion, fuel metering means in said fuel conduit, means operatively connecting said suction responsive means and said -metering means, said fuel conduit being open at all positions of said metering means, and

means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will be discharged into said bore portion and through said second-named passageway into said mixing chamber.

7. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing cham'- ber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a bore portion of restricted cross-sectional area, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into saidbore portion, said outlets being positioned in a common plane normal to the longitudinal axis of said bore portion whereby said conduits are subjected-equally to variations in pressure in said bore portion, a valve in said fuel conduit, a throttle valve controlling discharge from said first-named passageway, temperature responsive means operatively connecting said valves, and means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will be discharged into said bore portion and through said second-named passageway into said mixing chamber.

8. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a bore portion of restricted cross-sectional flow area, a liquid fuel reservoir, a. fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said bore portion, said outlets being positioned in a common plane normal to the longitudinal axis of said bore portion whereby said conduits are subjected equally to variations in pressure in said bore portion, two fuel metering valves in said fuel conduit, one of said valves being operatively connected to said responsive means, a throttle valve controlling discharge from said-first-named passageway, means operatively connecting the other of said metering valves to said throttle valve, said one metering valve controlling fuel flow at substantially closed and at substantially wide open throttle valve positions, said other metering valve controlling fuel flow at intermediate throttle valve positions, and means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will be discharged into said bore portion and through said second-named passageway into said mixing chamber.

9. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an' air inlet, suction responsive means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a bore portion of restricted cross-sectional area, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, said conduit having a portion of its length extending above the liquid level in said reservoir, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said bore portion, said outlets being positioned in a common plane normal to the longitudinal axis of said bore portion whereby said conduits are subjected equally to variations in pressure in said bore portion, means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit so that fuel will be discharged into said bore portion and through said second-named passageway into said mixing chamber by the maintained pressure difierential, and means to supplement the discharge of fuel supplied by the maintained pressure differential.

10. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging intosaid mixing chamber, said second-named passageway having a bore portion of restricted cross-sectional fiow area, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said bore portion, said outlets being positioned in a common plane normal to the longitudinal axis of said bore portion whereby said conduits are subjected equally to variations in pressure in said bore portion, a pump in said fuel conduit, means operatively connecting said pump to said suction responsive means, and means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will be discharged into said bore portion and through said second-named passageway into said mixing chamber.

11. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a converging-diverging bore portion, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, said conduit having a portion of its length extending above the liquid level in said reservoir, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said bore portion, said outlets being positioned in a common plane normal to the longitudinal axis of said bore portion whereby said conduits are subjected equally to variations in pressure in said bore portion, a pump supplied from said reservoir, a discharge conduit leading from said pump and discharging into said converging-di-- verging bore portion, and means to maintain a greater pressure in said reservoir above the liq,- uid level therein than exists in said fuel conduit whereby fuel will be discharged into said bore portion and through said second-named passageway into said mixing chamber.

12. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air ,to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway.

having a converging-diverging bore portion, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and having an outlet at and discharging into said bore portion, a vapor withdrawal conduit leading from said reservoir above the liquid level therein and having an outlet discharging into said bore portion, said outlets being positioned in a common plane normal to the longitudinal axis of said bore portion whereby said conduits are subjected equally to variations in pressure in said bore portion, a pump supplied from said reservoir, a discharge conduit leading from said pump and opening into said second-named conduit anterior to said bore portion, means in said discharge conduit to close said discharge conduit against indrawing of air to said pump, and means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will be discharged into said bore portion and through said second-named passageway into' said mixing chamber.

'13. A carburetor comprising a main casing having a passageway therethrough including a mixing chamber having an air inlet, an air valve responsive to mixing chamber suction and conmetering rod extending through said fuel port and defining with said wall an annular orifice, said rod having one end connected to said piston, means operatively connecting the other end of said rod to said air valve, and means carried by said main casing to move said housing memberrelative to said rod thereby to regulate the flow of said orifice.

14. A carburetor comprising a main casing having a passageway therethrough including a mixing'chamber having an air inlet, an air valve responsive to mixing chamber suction and controlling the admission of air to said chamber, a fuel supply conduit discharging into said mixing chamber, a casing carried by said main casing, a housing member containing a dash-pot chamber reciprocal in said second-named casing, a sleeve member slidably fitting and terminating in said conduit and extending from said housing member, said sleeve member having a fuel port establishing communication between said dashpot chamber and said conduit, a piston in said dash-pot chamber, a fuel metering rod extending through said fuel port and having one end connected to said piston, means operatively connecting the other end of said rod to said air valve, and means carried by said main casing to move said housing member to regulate fuel flow through said port.

, 15. A carburetor comprising a main casing having a passageway therethrough including a mixing chamber having an air inlet, an air valve responsive to mixing chamber suction and controlling the admission of air to said chamber, a fuel supply conduit discharging into said mixing chamber, a casing carried by said main casing, a housing member containing a dash-pot chamber reciprocal in said second-named casing and having a sleeve member slidably fitting in said conduit, said sleeve member having a fuel port, a piston in said dash-pot chamber, a fuel metering rod extending through said fuel port and having one end connected to said piston, means operatively connecting the other end of said'rod member, and a pinion engaging said rack to' move said housing member to regulate fuel flow through said port.

16. A carburetor comprising a main casing having a passageway therethrough including a mixing chamber having an air inlet, an air valve responsive to mixing chamber suction and controlling the admission of air to said chamber, a fuel supply conduit discharging into said mixing chamber, a casing carried by said main casing, a housing member containing a dash-pot chamber reciprocal in said second-named casing and having a fuel port communicating with smd conduit, a partition dividing said. housing member into a dash-pot chamber and a fuel passage feeding said port, a supplemental fuel supply conduit leading from said dash-pot chamber and discharging into said mixing chamber, a piston in said dash-pot chamber operable to force fuel through said supplemental conduit, 9. fuel metering rod extending through said fuel port. and into said passage, means connecting said rod to said piston, means connecting said rod to said air valve, and means to move said housing member to regulate fuel fiow througl said port.

1'7. A carburetor comprising a casing having a. main passageway therethrough including a mixing chamber having an air inlet, a suction responsive air valve in said passageway and controlling admission of air to said mixing chamber, a wall of said casing having a passageway bypassing said air valve and communicating at its outlet end with said main passageway, said bypass passageway having a converging-diverging bore portion defining a throat, a fuel supply conduit discharging laterally into said throat, a dash-pot chamber receivingliquid fuel and having communication with said by-pass passageway, a piston in said dash-pot chamber, said casing having a guide bore opening into said conduit, means operatively connecting said air valve to said piston and extending through said bore and into said fuel conduit, and a fuel metering valve carried by said connecting means and controlling flow through said conduit.

18. A carburetor comprising a casing having a main passageway therethrough including a mixing chamber having an air inlet, a suction responsive air valve in said passageway and controlling admission of air to said mixing chamber, a passageway by-passing said air valve and communicating at its outlet end with said main passageway, said by-pass passageway having a converging-diverging bore portion defining a threat, a fuel supply conduit discharging into said throat, a dash-pot chamber receiving liquid fuel and having communication with said by-pass passageway, a piston in said dash-pot chamber, mrans operatively connecting said air valve to said piston, said connecting means extending into said fuel conduit, a fuel metering valve carried by said connecting means, a reciprocatory sleeve member in said conduit and having a port receiving said metering valve, and means to move said sleeve member to regulate fuel flow through said conduit.

19. A carburetor comprising a main casing having vertical downward discharging passageways therethrough with aligned fiat internal wall portions, a shaft having its side face in contact with said wall portions, an air valve plate member in each passageway, said valve members being secured at one edge to said shaft and extending at a downward inclination therefrom, said casing having a guide bore extending at a downward inclination between said passageways from a point adjacent the underside and intermediate lhe ends of said shaft, a reciprocal rod guided in said bore, means operatively' connecting one end of said rod to said shaft, a dash-pot and pump casing carried by said main casing and receiving the other end of said rod, a housing member having an end wall and reciprocal in said dash-pot casing, a sleeve member projecting from said end wall and reciprocally fitted in said bore, said sleeve member having a fuel orifice receiving said rod, said rod having a metering valve portion cooperable with and controlling fuel fiow through said orifice, means to reciprocate said housing member, a piston in said housing' memher and secured to and movable with said rod, a. float chamber casing carried by said main casing in overlying relation to said dash-pot casing, a fuel conduit connecting the interiors of said float chamber casing and said dash-pot casing, said main casing having in its wall opposite said shaft a vertical bore having its inlet end open to atmosphere, a transverse bore communicating with said vertical bore and having outlets discharging into said passageways posterior to said valve members, a tube in said vertical bore and having a converging-diverging bore forming a throat, a fuel conduit leading from said guide bore on the outlet side of said orifice and discharging into said throat, an air suction conduit leading from the interior of said float chamber casing and discharging into said throat, throttle valves posterior to said air valve members and controlling discharge from said passageways, and means to equalize the suctions in said passageways anterior to said throttle valves.

20. A carburetor comprising a main casing having vertical downward discharging passageways therethrough with aligned flat internal wall portions, a shaft having its side face in contact with said wall portions, an air valve-plate member in each passageway, said valve members being secured at one edge to said shaft and extending at a downward inclination therefrom, said casing having a guide bore extending at a. downward inclination between said passageways from a point adjacent the underside and intermediate the ends of said shaft, a reciprocal rod guided in said bore, means operatively connecting one end of said rod to said shaft, 9. dash-pot and pump casing carried by said main casing and receiving the other end of said rod, a housing member having an end wall and reciprocal in said dash-pot casing, a sleeve member projecting from said end wall and reciprocally fitted in said bore, said sleeve member having a fuel orifice receiving said rod, said rod having a metering valve portion cooperable with and controlling fuel flow through said orifice, means to reciprocate said housing member, a. piston in said housing member and secured to and movable with said rod, cooperable tubular members separating the interior of said housing member into a central fuel conduit opening into said sleeve member and an annular dash-pot and pump chamber containing said piston, a float chamber casing carried by said main casing in overlying relation to-said dash-pot casing, a fuel conduit connecting the interiors of said float chamber casing and said dashpot casing for supplying fuel to said annular chamber and to said tubular members, said main casing having in its wall opposite said shaft a pair of vertical bores having their inlet ends open toatmosphere and having their outlet ends discharging respectively into said passageways posterior to said air valve members, a tube fitted in each of said vertical bores and having a converging-diverging bore forming a throat, a main fuel conduit leading from said guide bore on the outlet side of said fuel orifice and discharging into said throats, air suction conduits leading from the interior of said float chamber casing and discharging into said throats, pump discharge conduits leading from said pump casing to said air suction conduits, the end wall of said housing member being ported to establish communication between said annular pump chamber and said discharge conduits, and means to prevent withdrawal of fuel by suction from said discharge conduits.

21. A carburetor comprising a casing having an open-ended downward discharging substantially vertical passageway therethrough, the open upper end-of said passageway defining an air inlet and the open lower end of said passageway defining a. mixture outlet, the wall of aid casing having an open-ended bore extending longitudinally of said passageway and having its upper end defining an air inlet and its lower end defining a mixture outlet, said bore opening laterally into said passagewayand having a tubular extension spacing the outlet of said bore from the walls of said passageway, suction responsive means controlling admission of air to said passageway and positioned in overlying relation to said tubular extension, said bore having a converging-diverging portion forming a throat, a fuel supply conduit discharging into said throat to supply a mixture of air and fuel to said passageway, movable fuel metering means controlling said conduit, and means operatively connecting said suction responsive means and said metering means.

22. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an .air inlet, suction responsive means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passagewayfirst-named passageway, means operatively connecting said throttle valve and said metering means, and means to maintain a greater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will r be discharged into said bore portion and through said second-named passageway into said mixing chamber.

23. A carburetor comprising a casing'having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air to said mixing chamber and operable to maintain the sub-atmospheric pressure in said mixing chamber within predetermined limits, a liquid fuel reservoir, a fuel supply conduit leading from said reservoir below the liquid level therein and discharging into said mixing chamber, two fuel metering valves in said fuel conduit, one of said valves being operatively connected to said suction responsive means, a throttle valve controlling discharge from said passageway, means operatively connecting the other of said metering valves to said throttle valve, said one metering valve controlling fuel flow at substantially closed and at substantially wide open throttle valve positions, said other metering valve controlling fuel flow at intermediate throttle valve positions, and means to maintain a greater pressure in said reservoir above the licfuid level therein than exists in said fuel conduit.

24. A carburetor comprising a casing having a passageway therethrough including a mixing chamber having an air inlet, suction responsive means controlling the admission of air to said mix c amber and ope able to ma nta n the sub-atmospheric pressure in said mixing chamber within predetermined .limits, a passageway having an air inlet and discharging into said mixing chamber, said second-named passageway having a converging-diverging bore portion, a liquid fuel open throttle valve positions, said other metering valve controlling fuel flow at intermediate throttle valve positions, and means to maintain agreater pressure in said reservoir above the liquid level therein than exists in said fuel conduit whereby fuel will be discharged into said bore portiomand throughsaid second-named'passageway into said mixing chamber.

25. A carburetor comprising a main casing having a passageway therethrough with an air inlet, a fuel supply conduit discharging into said passageway, a.-casing enclosing a dash-pot chamber communicating with said conduit, a tubular member reciprocal in said conduit, a piston in said chamber, suction responsive means controlling admission of air'from said air inlet to said passageway, a fuel metering member extending into said tubular member and cooperating therewith to control the fuel flow through said conduit, said metering member interconnecting said suction responsive means and said piston, and means to adjust said tubular member relative to said metering member to regulate the ratio of fuel to air supplied to said passageway.

26. A carburetor comprising a main casing having a passageway'therethrough with an air inlet, a fuel supply conduit discharging into said passageway, a casing enclosing a dash-pot chamber communicating with said conduit, a tubular member reciprocal in said conduit, packing materialsealing the space between said tubular member and the wall of said conduit, a piston in said chamber, suction responsive means controlling admission of air from said air inlet to said passageway, a fuel metering member extending into said tubular member and cooperating therewith to, control the fuel flow through said conduit; said metering member interconnecting said suction responsive means and said piston, a shaft carried by, saidmain casing, and cooperable means on said shaft and said tubular member operable upon rotation of said shaft to adjust said tubular member relative to said metering member to regulate the ratio of fueltb air supplied to said passageway.

27.'A carburetor comprising a main casing having a passageway therethrough with an air inlet, a fuel supplyconduit discharging into said passageway, a, casing enclosing a dash-pot chamber communicating with said conduit, a tubular member reciprocal in said conduit, 2. piston in said chamber, a tubular member extending from said piston concentrically with said first-named tubular member and having longitudinal sliding.

members comprising a passageway establishing communication between said reservoir and said conduit, suction responsive means controlling admission of air from said air inlet to said passageway, a fuel metering member extending into said first-named tubular member and cooperating therewith to control the fuel fiow through said conduit, said metering member interconnecting said suction responsive means and said piston, and means to adjust said first-named tubular member relative to said metering member to regulate the ratio of fuel to air supplied to said passageway. N

28. A carburetor comprising a main casing having a passageway therethrough including a mixing chamber having an air inlet, an air valve responsive to mixirg chamber suction and controlling admission of air to said chamber, a fuel supply conduit discharging into said chamber, a casing carried by said main casing and containing a dash-pot chamber, a piston in said dashpot chamber, a fuel metering rod operatively connected to said valve and to said piston, a pair of concentric relatively movable tubular members surrounding said rod and extending between said conduit and said piston, said tubular members being laterally spaced from said rod and from the side walls of said dash-pot chamber and having a port cooperable with said rod to provide a fuel orifice, means to supply fuel to the interior of said tubular members for fiow to said conduit, and means cooperable with the tubular member having said port to adjust said member relative to said rod to control the ratio of air to fuel supplied to said mixing chamber.

29. A carburetor comprising a casing having a. main passageway therethrough including a mixing chamber having an air inlet, a suction responsive air valve in said passageway and controlling admission of air to said mixing chamber, a passageway by-passing said air valve and communicating at its outlet end with said main passageway, said by-pass passageway having a converging-diverging bore portion defining a throat, a fuel supply conduit discharging into said throat, a dash-pot chamber receiving liquid fuel and having communication with said bypass passageway, a piston in said dash-pot chamber, a rod member extending through a side wall of said fuel conduit into said dash-pot chamber and operatively engaging said piston, said rod member'having operative connection with said air valve such that movement of said air valve will be transmitted to said piston, a reciprocatory sleeve member in said conduit and surrounding said rod member, said rod member having a tapered portion cooperable with the bore of said sleeve member to meter fuel flow through said fuei'conduit, and ,means to adjust said sleeve member longitudinally of said rod member to control the ratio of fuel to air supplied to said main passageway.

30. A carburetor comprising a casing having a main passageway therethrough including a mixing chamber having an air inlet, a suction responsive air valve in said passageway and controlling admission of air to said mixing chamber, a passageway by-passing said air valve and communieating at its outlet end with said main passageway, said by-pass passageway having a converging-diverging bore portion defining a throat, a fuel supply conduit discharging into said throat, a dash-pot chamber receiving liquid fuel and having communication with said by-pass passageway, a piston in said dash-pot chamber, means operatively connecting said air valve to said piston, said connecting means extending into said fuel conduit, a fuel metering valve carried by said connecting means, a reciprocatory sleeve member in said conduit and having a port receiving said metering valve, a spring interposed between said sleeve member and said piston and opposing operation of said air valve by mixing chamber suction, and means to move said sleeve member to increase simultaneously the resistance of said spring to air valve movement and to increase the effective .fiow area of said port.

31. A carburetor comprising a main casing having a vertical downward discharging passageway therethrough with' a fiat internal wall portion, a shaft extending transversely through said passageway at said portion, the shaft side face closely fitting with the wall of said passageway, an air valve plate member conforming to said passageway and secured at one edge to said shaft, said valve member extending at a downward inclination from said shaft and having downward swinging opening movement, said casing having a guide bore extending at a downward inclination from the underside of said shaft, a reciprocal rod guided in said bore and projecting from the ends thereof, means operatively connecting one end of said rod to said shaft, a dash-pot casing carried by said main casing and receiving the other end of said rod, a sleeve member reciprocally fitted in said bore and projecting into said dashpot casing, said sleeve member having a fuel orifice receiving said rod, said rod having a tapered portion intermediate its ends and cooperable with said orifice, means to reciprocate said sleeve member, a piston in said dash-pot casing and operatively connected to said rod, means to supply fuel to said dash-pot casing for flow through said orifice, the wall of said main casing having a downward extending bore having its upper end comprising an air inlet and having its lower end discharging into said passageway posterior to said valve member, a tubular member in said lastnamed bore and having a converging-diverging bore forming a throat, a fuel conduit leading from said guide bore on the outlet side of said orifice and discharging into said throat, and a throttle valve in said passageway and controlling discharge therefrom.

32. A carburetor comprising a main casing having a vertical downward discharging passageway therethrough with a fiat internal wall portion, a shaft extending transversely through said passageway at said portion, the shaft side face closely fitting with the wall of said passageway, an air valve plate member conforming to said passageway and secured at one edge to said shaft, said valve member extending at a downward inclination from said shaft and having downward swinging opening movement, said casing having a guide bore extending at a downward inclination from the underside of said shaft, a reciprocal rod guided in said bore and projecting from the ends thereof, means operatively connecting one end of said rod to said shaft,- a dash-pot and pump casing carried by said main casing and receiving the other end of said rod, a housing member having an end wall reciprocal in said dash-pot casing, a sleeve member projecting from said end wall and reciprocally fitted in said bore, said rod having a tapered fuel metering portion cooperable with the bore of said sleeve member to define an annular operatively connected to said rod for movement 

